/Engine/Plugins/Editor/GameplayTagsEditor/Source/GameplayTagsEditor/Public/GameplayTagsEditorModule.h
Adds a new tag source, well use project config directory if not specified. This will not save anything until a tag is added
bool AddNewGameplayTagSource ( const [FString](API\Runtime\Core\Containers\FString) & NewTagSource, const [FString](API\Runtime\Core\Containers\FString) & RootDirToUse )